Control arrangements for hydraulic pit prop support units



Nov. 18, 1969 H. RlEscHl-:L 3,478,522

CONTROL ARRANGEMENTS FOR HYDRAULIC PIT PROP SUPPORT UNITS Filed Jan. 29, 1968 3 Sheets-Sheet 1 Nv. 18, 1969 H. RlEscHl-:L 3,478,522

CONTROL ARRANGEMENTS FOR HYDRAULIC PIT PROP SUPPORT UNITS Filed Jan. 29, 1968 3 Sheets-Sheet 2 /74 FIG. 2 /02 Nov. 18, 1969 H. RlEscHEL. 3,478,522

CONTROL ARRANGEMENTS FOR HYDRAULIC PIT PROP SUPPORT UNITS Filed Jan. 29, 1968 3 Sheets-Sheet 3 2l WZL/M lw Unted States Patent O" 3,478,522 CONTROL ARRANGEMENTS FOR HYDRAULIC PIT PROP SUPPORT UNITS Hans Rieschel, Essen-Holsterhausen, Germany, assignor to Bergwerksverband G.m.b.H., Essen, Germany, a company of Germany Filed Jan. 29, 1968, Ser. No. 701,401 Claims priority, application Germany, Feb. 2, 1967,

B 91,001; Feb. 14, 1967, B 91,168 Int. Cl. E21d 23/04; F01b 31/12, 25/26 U.S. Cl. 61-45 5 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a control and regulating arrangement for maintaining a predetermined angle between the longitudinal axis of a feed cylinder or jack of a hydraulic pit prop support unit and the longitudinal axis of a strongpoint support also set up in the mine working, in particular the longitudinal axis of a conveyor, the feed cylinder or its piston rod being iixed to the strongpoint through a pivotal joint and the unit being equipped, for purposes of reaction against the neighbouring support unit, with an aligning or jacking cylinder disposed transversely of the feed direction, which cylinder becomes operative automatically during the advancing operation of the support units, and is characterised by the provision of a controller incorporating a servo-device responsive to variation in the angle between the feed mechanism axis and the strongpoint axis and acting on the pit prop support unit to restore said angle to the predetermined value.

BACKGROUND OF THE INVENTION Arrangements of this kind are intended to avoid the risk of breakdowns or accidents which could arise from the fact that, because of differing local conditions, in particular the effects of gravity in dip workings, the casing frames can swing around the joint locating the feed cylinder as soon as the pit props are collapsed.

PRIOR ART To the extent that the casings of the support units, in the form of casing frames, are equipped with devices which guide two neighbouring units in relation to one another, rails, combinations of springs and rails, and also hydraulic jacks arranged on the casing heads, are employed. However, these devices do not operate satisfactorily. The reason for this is obviously to be found in the principle upon which they are based, since they presuppose that the unit, when xed in position, will be in the proper nominally required attitude, but this is not the case after several advancing steps have taken place because, for one thing, the unavoidable tolerances which are present tend to accumulate.

In accordance with other proposals which have been made, the feed mechanism (cylinder or piston) is associated with relatively rigid bars which, in the event that the units deviate from the proper direction of advance, distort and provide an elastic restoring force to correct the direction of advance. The danger then exists however, that with severe deviations in the attitudes of the units, these bars will take permanent set, so that the elastic restoring forces will no longer be suicient to produce proper correction. Moreover, the use of bars of this kind give rise to a not insubstantial degree of extra expense and complication.

These, and other kinds of units in the form of casing frames whose feed cylinders are linked through cables to the conveyor, the cables being arranged in block and tackle fashion and the feed cylinders which guide ICC the units being housed in the slide, alter their advance direction automatically and follow the longitudinal movement of their point of attachment to the conveyor. Quite apart from the fact that changes in the advance direction are more often than not undesirable because of the associated local reduction in the pit prop density, these devices cannot be employed for ordinary casing jacks and cannot be used in situations where the feed cylinder is directly articulated to the strongpoint used for the feed mechanism.

straightforward casing jacks can accordingly only be employed in dipping seams at the expense of using extensive auxiliary mechanical equipment. Auxiliary equipment of this sort, however, will not operate with dips of between 30g and 100g, yso that hitherto it has not been possible to employ casing jacks in these situations. This is a considerable drawback because the casing jack is a comparatively simple and robust structure and its control is uncomplicated, factors which frequently make it preferable to other kinds of support units, such as casing frames. This applies in particular to the automatic maintaining of the support unit attitude in an attitude normal relative to the lie of the working when ordinary casing jacks are used, although with casing frames regulating devices, which do not yet form part of the state ofthe art, may be employed.

It is true that a method of casing a working using casing jacks is known, in which the jacks are connected through their feed mechanisms with a strongpoint and react, through a lining or jacking cylinder disposed transversely of the feed direction, against the particular neighbouring units. vIn this context, the aligning and jacking cylinders can be hydraulically coupled so that they are automatically operated during the advance process, with the con-sequence that the casing jacks are aligned. With this kind of arrangement too, however, the inevitable tolerances tend, as already mentioned, to accumulate in an unwanted manner.

In addition to this, it is already known to sense the position of casing frames or jacks in the mine working and to initate the advance operaton as a-function of this sensing. Using known devices of this kind, however, it is not possible to maintain a predetermined angle between the longitudinal axis of a feed cylinder of a hydraulic casing frame or of a casing jack, and the longitudinal axis of a strongpoint support (in particular a conveyor) for the feed mechanism.

OBJECT OF THE INVENTION The primary object of the invention is to provide an arrangement of the general kind referred to hereinbefore which will operate automatically without the need for considerable technical outlay and providing virtually any desired correcting forces, and which therefore particularly, although not exclusively, permits the use of ordinary casing jacks in situations in which, as pointed out earlier, they could hitherto not have been used without incurring certain disadvantages.

BRIEF SUMMARY OF THE INVENTION This object is achieved, in accordance with the basic principle of the invention by virtue of the fact that an automatic regulator is provided for each pit prop support unit which, independence upon the angular position of the feed -cylinder in relation to the strong point support, operates a jacking cylinder acting as servomotor, this jacking cylinder being connected to the neighboring pit prop support unit (casing frame or casing jack) through two joints.

With this arrangement, the pit prop suport unit still tends, when the pit props are collapsed, to pivot about the horizontal joint, but this causes the regulator to respond. The regulator generates an opposing couple through the medium of its servomotor, which holds the casing jack and therefore the feed cylinder in the desired angular position throughout every phase of the advance operation, so that the advance direction remains constant. The regulator at the same time cancels out the couples which the jacking cylinder may tend to produce because of its articulation to the neighbouring stationary casing jack.

An important factor in achieving proper operation of the regulator is robust and simple design of the measuring device which it uses to determine the controlled quantity. In accordance with a further feature of the invention, this measuring device consists of sensing plungers arranged at either side of the said joint between the feed mechanism and the strongpoint support and movable in the axial plane of the feed mechanism, the plungers being attached to one of the parts of the joint. The sensing plungers co-operate with a fixed datum on the other part of the joint, and are depressed and operated when they come into contact therewith.

Sensing plungers of this kind are used amongst other things because they are capable of controlling pressurised media. Media of this sort are used in pneumatic and hydraulic techniques of mine casing work, instead of electrical switching signals, because of the risk of explosion.

It is particularly advantageous to follow the measuring device by a heavy duty switching arrangement. This arrangement is controlled by the low pressure signals, in particular pneumatic signals, supplied by the measuring device, and in turn feeds a high pressure medium, in particular hydraulic fluid, to one side or the other of the piston in the jacking cylinder. A pneumatic-hydraulic conversion signal of this sort, for the regulation signals, makes a substantial contribution to a reduction in technical outlay, because of the fact that a major part of the regulator then operates at low pressure although high working pressures are being controlled.

In a practical embodiment of the invention, the two sensing plungers are conveniently formed as parts of twoway valve spools. These two-way valves are in turn followed by diaphragm control valves, one for each side of the feed mechanism, these latter valves performing the heavy duty switching function.

The invention furthermore relates to a valve generally employed to control hydraulic or pneumatic systems, which is diaphragm-operated by compressed air, and is used in particular in hydraulic mine casing techniques; it is particularly suitable as a heavy duty switching device following the measuring device.

Valves of this kind, which can be employed quite generally in control systems, but which are particularly suitable for the control and regulation of hydraulic casing operations underground and which enable pneumatic control of the hydraulic system to be effected, have the advantage of providing the kind of precision in control which sensitive regulation requires, a precision which is frequently not obtainable with signals of mechanical nature, and also the advantage of doing away with electrical systems which are often difficult to render safe for control operations in locations where there is a risk of explosion.

Valves with diaphragm control of this kind are well known. Hitherto, however, they have been relatively large units, that is to say they have been designed with considerable nominal cross-sections. In their known form, they frequently operate using an arrangement consisting of a diaphragm piston and a return spring. However, they cannot be suciently reduced in size to be employed in hydraulic casing operations in mines. Also, even if they could be reduced in size to this extent, they could then not be given sufficient mechanical resistance.

On the other hand, solenoid-operated valves are known which, using valve elements, in particular ball-type valve elements, operated by a plunger slidably mounted in a .4 valve housing, alternately open and close an output load, i.e. connect this output either with the return line or with the high pressure line. Apart from the disadvantages associated with the electrical control of the solenoid system, -which disadvantages have been set out hereinbefore, the problem also arises in this case of achieving suitable step-up or step-down between the diaphragm operating system and the valve elements. This generally means the introduction of levers which not only give rise to large dimensions in the overall arrangement, but also have the drawback from the control point of view that the sensitivity of operation is affected by the unavoidable backlash in the linkage. The consequence is undesirable characteristics and transient functions.

In accordance with the invention, the valve is so designed that while avoiding the aforementioned drawbacks and diiculties, it permits constructional arrangement of a substantially arbitrary nature and also variability of characteristics, and can itself be minaturised, in prticular in such a way that the hydraulic connections can be developed in an integrated circuit fashion, hydraulic circuit arrangements of this kind being very easy to house because of their small dimensions.

In this context, a further feature of the invention provides a housing suitable for the parallel arrangement of several diaphragm operating systems, in particular a housing which is flat on at least one side and in particular on at least two opposite sides, such housing serviing at least to accommodate the valve associated with each diaphragm operating system, and connecting elements, in particular in the form of xing or tie bolts, passing perpendicularly through bores which open into the said surface or surfaces, said bolts serving to hold together several such housings.

The valves and possibly the diaphragm operating housings, formed in this fashion, can be assembled together in a block or column. This can be achieved by attaching the valves to a common distributor plate but also by directly assembling together the housings with the aid of the tie bolts extending through them. The result is a substantially rectangular column to which the requisite feed and return lines can be attached without any particular problem.

Square or rectangular housings of this kind can be substantially reduced in size compared with known shutoff valves using a diaphragm operating system consisting of diaphragm piston and return spring, if their construction is so contrived that a housing accommodating the diaphragm piston, in particular a housing of square plan form, is attached to one end of the valve housing, the latter in particular having its plan form matched to that of the housing for the diaphragm piston, to the other end of which valve housing a further housing accommodating the return spring is attached, whilst the individal components of the valve are arranged in a communicating bore extending between the diaphragm piston and the spring. This also furnishes the essential advantage that the overall Valve assembly can be Withdrdawn en bloc and replaced by another, in particular a valve assembly having a different characteristic, as required.

By this measure, the result is achieved in fact that the 'actual valve is enclosed between the diaphragm operating system and the return spring, so that the diaphragm piston can act directly on the valve element, which is actuated through a plunger and takes the form of a ball,

at the other end of which valve element the spring acts,

in accordance with a further feature of the invention, that two through bores, which open out at the two at faces of the housing, are provided to do duty as the feed and return ports for the hydraulic or pneumatic source, then a very simple parallel arrangement of the load connections to these Ifeed and return lines, which extend through a column of said valves, is achieved.

In accordance with yet another feature of the invention, the provision of a manually operated button, to control the diaphragm operating system, creates the facility for hand operation in emergency.

The result is that the overall valve arrangement is so small, even where a plurality of loads is involved, that it can be used to carry out all the requisite control and regulating functions with the requisite high speed, in particular in the context of hydraulic mine casing systems.

DESCRIPTION OF DRAWINGS Further features and advantages of the invention will emerge from the following description given by way of example only with reference to the accompanying drawlngs.

In the drawings:

FIGURE 1 is a plan view of part of a dip working, with a hydraulic'pit prop support unit and its control arrangement;

FIGURE 2 is a sectional view of a valve for use in the arrangement according to the invention;

FIGURE 3 is a plan view of the valve of FIGURE 2;

FIGURE 4 is a side elevation of the valve of FIG- URE 2; and

FIGURE 5 illustrates the manner in which several valves may be installed.

In accordance with FIGURE 1, a conveyor 2 is positioned alongside the coal seam 1, the conveyor serving as a strongpoint to take the reaction arising out of the advancing movement to a pit prop support unit in the form of a jack system 3 consisting of a casing incorporating four pit props 4 and two casing heads 5. A feed cylinder 6 has its piston rod 7 articulated through a joint 8 to a block 9, which is in turn iixed to the rear of the conveyor.

A line 10 carrying hydraulic fluid runs alongside the conveyor and supplies all the hydraulic parts of the jack system 3. Also provided alongside the working is a low pressure air line 11.

In the example illustrated, the conveyor end of the piston rod 7 is mounted in a yoke 12 with a flange 13 to which two pneumatic three-way valves are attached one on either side of the piston rod. Where necessary for distinguishing purposes, the upper valve in the drawing is designated 14, and the components and circuit lines associated therewith are given the suffix a following the same reference numerals as the components and circuit lines associated with the lower valve.

The valves 15 are identical in design, each being equipped with a sensing plunger 16 co-operating with a flat surface forming a switching datum 17, the latter being formed on the block 9. Each valve 15 has an air bleed hole 18, a connection 19 to the air line 11 and an output line 20 leading to a chamber, closed oif by a diaphragm 21, in a diaphragm-controlled hydraulic valve 22. A

The hydraulic part of the valve 22 is connected by a line 23 to the hydraulic line 10 and is provided with a return port 24. The diaphragm 21 controls the position of two `ball valves 25 which, in the manner indicated in the lower part of the drawing, in one position connect the line 23 to a line 26, or, in the manner indicated in the upper part of the drawing, connect the line 26a to the return line 24a- As will be apparent, the line 26 leads to the piston rod space 27 of a hydraulic jacking cylinder 28, whilst the line 26a leads to the other space 29, above the piston in this same jacking cylinder 28.

The hydraulic jacking cylinder 28 is connected at a point 30 to an adjacent jack system, which is not shown in detail, for example to one of its pit props, and the arrangement is such that the jack system 3 only advances when the adjacent jack system is xed and static. The end of a piston rod 31 of the hydraulic jacking cylinder 28 is articulated at a point 33 to the rear of the casing jack system 3, at the sill end thereof.

If in order to move the jack system 3 forward, its hydraulic pit props 4 are depressurised and retracted, then the system 3 tends to swing, one way or another, for example into the position shown in an exaggerated manner in the drawing. Consequently, the plunger 16 of the lower valve 15 -is depressed against the force of a spring and allows the line 19 to communicate with the line 20, so that the diaphragm 21 is forced down. Accordingly, the ball valves 25 operate to bring the line 23 into cornmunication with the line 26, as a consequence of which the space 27 in the jacking cylinder 28 is pressurised. The result is that the piston rod 31 retracts into the cylinder 28, swinging the jack system 3 back in the direction of the arrow b until, under the inuence of the spring, the plunger 16 regains its former position.

In this position, the valve land associated with the plunger communicates the line 19 With the air bleed port 18, so that the diaphragm 21 lifts and the balls are placed in the position shown at valve 22a, in which position the line 26 communicates with the return line 24. As a consequence, the pressure in the cylinder 28, at the piston rod side, collapses and the swing of the system in the direction of the arrow b is stopped.

It can be seen that as soon as the jack system 3 reverts to its predetermined attitude, neither of the plungers 16 will be depressed by contact with the datum 17, so that the jacking cylinder 28 becomes inoperative.

The arrangement described constitutes a controller, the controlled quantity being the angle made between the direction of advance of the jack system 3 and the longitudinal direction of the conveyor 2, or more exactly the line determined by the datum 17. The servomotor of the controller is constituted by the jacking cylinder 28.

The measuring device is formed by the two valves 15 whilst the necessary heavy duty switching device is constituted by the two valves 22 and 22a.

In the example illustrated, the controller has a zero adjustment facility. To this end, the valves 15 are designed to be movable in the axial direction of the yoke and can be adjusted to a particular position by means of adjuster screws 40.

In contrast to what is shown in the above example, the block 9 on which the datum 17 is formed need not be attached to the conveyor in the manner suggested. In individual instances, it may instead be advisable to provide a fixing on the conveyor by means of which the datum can be moved in relation to the conveyor 2 when the latter has to be moved along the coal face. This movement of the conveyor can then be done without shifting the position of the joint 8, If required, the idea of attaching the block 9 to the conveyor can be discarded altogether, if this is substituted by a corresponding other strongpoint.

The articulation of the jacking cylinder 28 to the points 30 and 33 is the simplest solution available and therefore the most convenient. The controller described then also takes into account the effects which arise out of pivoting of the cylinder 28 about its xing point 30. Equally, however, longitudinal guiding of the jacking cylinder 28 in relation to the neighbouring jack system is possible.

The advantages thus achievable, in accordance with the invention, consist above all in the facility for exerting arbitrarily large restoring forces on the jacky system 3. Also, this is effected automatically and using a very simple control circuit, operated at low pressure and so small in size that it can be housed at the end of the piston rod 7 in a block.

A preferred practical switching valve is illustrated in FIGURES 2 to 4, and consists of two main sections, namely a valve 100 with a diaphragm operating system 102 which is described below in detail. The valve is accommodated in a housing 103 of square plan form in the present embodiment, which thus has four vertical sides 104, 105, 106 and 107. The valve housing 103 has a generally right rectangular form and therefore possesses, in addition to the sides already mentioned, sides 108 and 109 at right-angles thereto (see FIGURE 4).

This kind of design gives rise to two mutually opposite flat faces 106 and 105. Perpendicularly to these faces 106 and 105 extend four bores of the same diameter throughout, which accommodate tie bolts 111 (FIGURE so that a block assembly, made up of several of the devices shown in FIGURES 2 to 4, can be created. The diaphragm operating system is accommodated in a housing 112 the elevational and plan form of which correspond to the elevation and plan forms of the housing 103 already described in relation to the valve. The housing 112 is attached to the housing 103 by means of four screws 113 (see FIGURE 3).

At its top side, at the point 114 (see FIGURE 2), the connection for the compressed air is to be seen. By means of a bushing 115, beading 116 on a flexible diaphragm 117 acting upon a piston 118 is trapped between the inside wall of the housing and the bushing. The diaphragm operating system also incorporates a return spring 119 in a spring cap 120, the cap 120 being screwed into the end 108 of the valve housing 103, as the illustration shows. The housing 103 also has an outlet or load connection 121 (see FIGURE 2 and 4).

From the connection 121 a bore 122 extends into the housing 103, terminating in an axial bore 123. In the axial bore 123 there slides a plunger 124, against the ends of which, in this particular example, bear ball-type value elements 125. A plunger 126 is carried at one end at point 127 in the diaphragm piston 118, and at the other end at point 128 seats on one of the valve elements 125. The other valve element 125 seats on one end 129 of an additional plunger 130 with an enlarged head portion 131 against which bears the spring 119 of the diaphragm operating system. At the exit points of the bore 123 in the element 132 are formed seats for the two valve elements 125.

As FIGURE 4 shows, the overall system has a connection 140 on each of the said ilat faces 106 and 105 on the housing 103, these connections being for a pump, and similar connections 141 on each face for the return line to a reservoir.

For the rest, the system of bores inside the housing 103 is so contrived that, all in accordance with which of two possible positions the two valve elements 125 adopt, the load connection 121 is in communication with the reservoir (return line) or with the pump (supply line). Such systems of bores are well known and the particular arrangement illustrated requires no further explanation here.

If, in the device illustrated, the space above the diaphragm 117 is filled with compressed air, then the piston 118 shifts the plunger 126 and thus moves the upper of the two valve elements 125 shown in FIGURE 2 on to its seat. When the pressure in the space above the diaphragm 117 collapses, the spring 131- returns the lower of the two valve elements shown in FIGURE 2 to itsvseat, and lifts the other valve element away from its seat.

As FIGURE 5 indicates, several of the complete switching devices explained hereinbefore and illustrated in detail in FIGURES 2 and 4, can be assembled together to form a block or column. All that this requires is a T-shaped junction piece 130, with a connection face 151,

to which junction piece a virtually unlimited number of the said devices can be connected through the medium of the tie bolts 111 already described. The load connections 121 then exit at one side, although the arrangement could easily be contrived in such a fashion that some of the connections 121 exit at one side and others at the other side.

The main lines 153 and 154 terminate at the face 152, in cocks 155 and 156. These lines lead to the reservoir or to the pump.

There is also provided facility for manual operation by means of a button which operates the diaphragm operating system, although this has not been indicated in the drawing.

As can be seen, in this way a switching block can be achieved which is extremely compact, and which is distinguished by direct control channels and very sensitive control characteristics.

I claim:

1. In a travelling pit prop system for a mine working, which system comprises a plurality of pit prop support units for individual advance in steps relative to a strongpoint support, each unit including a feed cylinder and piston rod one of which is connected to the strongpoint support through a pivotal joint, the improvement consisting in the combination, for each support unit, of an aligning jack; a pivotal joint between the corresponding support unit and the aligning jack; a pivotal joint between the aligning jack and a neighbouring support unit; Sensing means responsive to the angle between the axis of the feed cylinder and a predetermined required direction of advance; and control means responsive to the sensing means and for operating the aligning jack as a servomotor to pivot the support unit, about its joint with the strongpoint support, to reduce the said angle to zero, advance of the said unit relative to the said neighbouring unit then being permitted by the said two pivotal connections associated with the aligning jack.

2. The combination according to claim 1, wherein the sensing means comprises sensing plungers attached to one part of the said joint between the support unit and the strongpoint support, and a datum for co-operation with said plungers attached to the other part of said joint.

3. The combination according to claim 2, wherein the control means comprises a fluid-pressure switching device adapted for operation by low pressure signals and controlling the supply of fluid under high pressure to the aligning jack.

4. The combination according to claim 3, wherein the sensing plungers are operatively incorporated in two-way valve spools which control respective diaphragm control valves constituting the fluid-pressures switching device.

5. The combination according to claim 1, wherein the control means comprises a fluid-pressure switching device adapted for operation by low pressure signals and controlling the supply of fluid under high pressure to the aligning jack.

References Cited UNITED STATES PATENTS 3,383,865 5/1968 Wilson et al. 61-45 OTHER REFERENCES 1,170,354 5/1964 Rheinstahl et al 61-45 German Printed Application JACOB SHAPIRO, Primary Examiner U.S. Cl. X.R. 91-1 

